[CIFS] improve setlease handling

fcntl(F_SETLEASE) currently is not exported by cifs (nor by local file
systems) so cifs grants leases based on how other local processes have
opened the file not by whether the file is cacheable (oplocked).  This
adds the check to make sure that the file is cacheable on the client
before checking whether we can grant the lease locally
(generic_setlease).  It also adds a mount option for cifs (locallease)
if the user wants to override this and try to grant leases even
if the server did not grant oplock.

Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 1126f7ab4606..f51b79a67e1b 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -90,7 +90,8 @@ struct smb_vol {
         bool nocase:1;     /* request case insensitive filenames */
         bool nobrl:1;      /* disable sending byte range locks to srv */
         bool seal:1;       /* request transport encryption on share */
-        bool nodfs:1;
+        bool nodfs:1;      /* Do not request DFS, even if available */
+        bool local_lease:1; /* check leases only on local system, not remote */
         unsigned int rsize;
         unsigned int wsize;
         unsigned int sockopt;
@@ -1264,6 +1265,10 @@ cifs_parse_mount_options(char *options, const char *devname,
                         vol->no_psx_acl = 0;
                 } else if (strnicmp(data, "noacl", 5) == 0) {
                         vol->no_psx_acl = 1;
+#ifdef CONFIG_CIFS_EXPERIMENTAL
+                } else if (strnicmp(data, "locallease", 6) == 0) {
+                        vol->local_lease = 1;
+#endif
                 } else if (strnicmp(data, "sign", 4) == 0) {
                         vol->secFlg |= CIFSSEC_MUST_SIGN;
                 } else if (strnicmp(data, "seal", 4) == 0) {
@@ -2162,6 +2167,7 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
                            for the retry flag is used */
                         tcon->retry = volume_info.retry;
                         tcon->nocase = volume_info.nocase;
+                        tcon->local_lease = volume_info.local_lease;
                         if (tcon->seal != volume_info.seal)
                                 cERROR(1, ("transport encryption setting "
                                            "conflicts with existing tid"));